• The Transactions of the Korean Institute of Power Electronics
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• v.19 no.4
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• pp.297-302
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• 2014

In this paper, a LED driver compatible with TRIAC-dimmer applying active bleeder is proposed. If TRIAC-dimmer is connected with LED driver, flicker phenomenon occurs by TRIAC malfunction. In order to prevent this problem, a current over holding current must flow into TRIAC. Therefore, additional circuit compatible with TRIAC-dimmer is required to provide enough current. Passive bleeder has power loss in whole operation period. The proposed circuit apply a valley-fill circuit for power-factor-correction and a novel active bleeder detecting malfunction point of TRIAC. Therefore, it prevent malfunction of TRIAC-dimmer and have advantage of higher efficiency than passive bleeder. To verify the validity of proposed circuit, 13W-lighting LED driver prototype has been proposed.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.1
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• pp.109-113
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• 2011

This paper analyzes the noise sources of an LED lighting module with TRIAC dimming control and proposes an improved EMI filter design for the reduction of conducted noise emission. TRIAC dimming invokes problems of input oscillation and capacitor overvoltage at the lighting module. The proposed double LC filter reduces high noise level from the circuit. The experimental and simulation results show that this approach can make significant contributions to the reduction of conducted noise emission from an LED lighting module with TRIAC dimming control.

• Journal of Power Electronics
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• v.15 no.2
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• pp.555-566
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• 2015

A TRIAC dimming LED driver that can control the brightness of LED arrays for a wide range of source voltage variations is proposed in this paper. Unlike conventional PWM LED drivers, the proposed LED driver adopts a TRIAC switch, which inherently guarantees zero current switching and has been proven to be quite reliable over its long lifetime. Unlike previous TRIAC type LED drivers, the proposed LED driver is composed of an LC input filter and a variable switched capacitance, which is modulated by the TRIAC turn-on timing. Thus, the LED power regulation and dimming control, which are done by a volume resistor in the same way as the conventional TRIAC dimmers, can be simultaneously performed by the TRIAC control circuit. Because the proposed LED driver has high efficiency and a long lifetime with a high power factor (PF) and low total harmonic distortion (THD) characteristics, it is quite adequate for industrial lighting applications such as streets, factories, parking garages, and emergency stairs. A simple step-down capacitive power supply circuit composed of passive components only is also proposed, which is quite useful for providing DC power from an AC source without a bulky and heavy transformer. A prototype 60 W LED driver was implemented by the proposed design procedure and verified by simulation and experimental results, where the efficiency, PF, and THD are 92%, 0.94, and 6.3%, respectively. The LED power variation is well mitigated to below ${\pm}2%$ for 190 V < $V_s$ < 250 V by using the proposed simple control circuit.

• Journal of Power Electronics
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• v.13 no.4
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• pp.609-618
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• 2013

This paper proposes a primary side constant power control scheme for TRIAC dimmer compatible LED drivers. The LED driver is a Flyback converter operated in boundary conduction mode (BCM) to minimize the switching loss. With the proposed control scheme, the input power of the Flyback converter can be controlled by the TRIAC dimming angle, which is not affected by AC input voltage variations. Since the output voltage is almost constant for LED loads, the output current can be changed by controlling the input power with a given conversion efficiency. The isolated feedback circuit is eliminated with the proposed primary side control scheme, which dramatically simplifies the whole circuit. In addition, the input current automatically follows the input voltage due to the BCM operation, and the resistive input characteristic can be achieved which is attractive for TRIAC dimming applications. Experimental results from a 15W prototype verify the theoretical analysis.

• Journal of Power Electronics
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• v.18 no.2
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• pp.640-650
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• 2018

A TRIAC dimmable LED driver with a wide tuning range and a two-stage uniform dimming scheme is proposed in this paper. To solve the restricted dimming range problem caused by the limited conduction ratio of TRIAC dimmers, a conduction ratio compensation technique is introduced, which can increase the output current up to the rated output current when the TRIAC dimmer turns to the maximum conduction ratio. For further optimization, a two-stage uniform dimming diagram with a rapid dimming curve and a slow dimming curve is designed to make the LED driver regulated visually uniform in the whole adjustable range of the TRIAC dimmer. The proposed control chip is fabricated in a TSMC $0.35{\mu}m$ 5V/650V CMOS/LDMOS process, and verified on a 21V/500mA circuit prototype. The test results show that, in the 90V/60Hz~132V/60Hz ac input range, the voltage linear regulation is 2.6%, the power factor is 99.5% and the efficiency is 83%. Moreover, in the dimming mode, the dimming rate is less than 1% when the maximum dimming current is 516mA and the minimum dimming current is only about 5mA.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.2
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• pp.84-94
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• 2013

In case when the existing TRIAC phase controlled dimmer is drove for the LED lighting equipments, there are many problems such as the LED flicker in low phase-angles, the acoustic noise and elements damage by increase of the peak voltage in the input filter capacitor, mulfunction by insufficiency of the TRIAC holding current, and the abnormal oscillation by LC resonant. In this paper, we proposes the single-stage quasi-resonant PSR(Primary Side Regulation) PWM converter, and the design, the simulation and experiment are performed. As a result, it could confirm that the proposed PWM converter is the lighting equipments for LED drive which can alternate the existing 60W class incandescent bulbs and it has the high drive performance of the efficiency 80% and over, the power factor 0.95 and over under the normal voltage 220V. Finally, total harmonic distortion(THD) is gratified with a standard[1] of the lighting equipments and the durability is evaluated as the high reliablilty of 150,000 hours and over.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.938_939
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• 2009

LED에 대한 관심과 개발이 지속되고 있는 현재 그 활용이 LCD 패널, 실내 외 조명등 실생활에 많이 이용되고 있다. 특히 실내 조명에서는 적용이 용이 하기 때문에 백열등과 형광등의 대체로 LED를 사용한다. 본 논문에서는 실내 조명 에너지 절감을 위하여 백열등 대체용 Triac 조도 제어 POWER LED 구동회로를 소개한다. Triac 위상 제어 회로는 백열등 전용으로 만들어 진 것이 대 다수이고 실내 조도 제어를 위해 많이 설치 되어 있다. Triac 위상 제어를 위한 POWER LED 구동 회로는 에너지 절감은 물론 백열등 대체 시 Triac 위상 제어 회로를 그대로 사용 할 수 있기 때문에 사회 전반에 걸쳐 사용 될 것으로 사료된다.

• KIEE International Transactions on Electrophysics and Applications
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• v.5C no.4
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• pp.152-154
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• 2005

We demonstrate a simple $CO_2$ laser by controlling firing angle of a TRIAC switch in ac power line. The power supply for our laser system switches the voltage of the AC power line (60Hz) directly. The power supply does not need elements such as a rectifier bridge, energy-storage capacitors, or a current-limiting resistor in the discharge circuit. In order to control the laser output power, the pulse repetition rate is adjusted up to 60Hz and the firing angle of TRIAC gate is varied from $45^{circ}$ to $135^{circ}$. A ZCS(Zero Crossing Switch) circuit and a PIC one-chip microprocessor are used to control the gate signal of the TRIAC precisely. The maximum laser output of 40W is obtained at a total pressure of 18 Torr, a pulse repetition rate of 60Hz, and a TRAIC gate firing angle of $90^{circ}$.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.9
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• pp.1283-1288
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• 2012

This paper presents speed control characteristics of capacitor-run SPIM(Single Phase Induction Motor) using TRIAC for comparing and analyzing four kinds of voltage control methods such as supply voltage control, main winding voltage control, auxiliary winding voltage control and auxiliary winding voltage control without starting capacitor. The computer simulations were performed using MATLAB Simulink to show control characteristics of four voltage control methods. And their control characteristics were conformed by experiments for capacitor-run 90W SPIM as a sample motor. The results of simulations and experiments show that supply voltage control method has fast dynamic response characteristics and main winding voltage control method has higher power efficiency and can be implemented at lower system cost.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.2 no.4
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• pp.75-81
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• 1988

TRIAC 위상제어 방식은 교류전류의 제어에 편리한 방법으로 많이 응용되고 있다. 유도전동기는 부하변화에 따라 역율과 효율이 변화하며 특히 무부하와 경부하에서는 큰 전력손실을 유발한다. 본 연구에서는 TRIAC 위상제어 방식을 이용하여 유도전동기의 기계적부하에 따른 최적의 전압을 공급함으로써 효율과 역율을 개선시켜 전력손실을 줄이는 것을 기본동작원리로 하며 종래의 구조의 복잡성과 경제성 및 실용성을 크게 개선 하는데 설계의 주된 목표를 두었다. 제안된 절전회로는 실험결과 부하의 변화가 빈번한 곳에 운용되는 소형유도전동기에서 상당한 절전효과가 나타났다.